1. Technical Field
The present invention is directed toward cycle brakes, and more particularly toward a cantilever brake for a cycle.
2. Background Art
Conventional cantilever brakes include include a pair of brake arms rotatably attached to a pair of attachment studs extending from the frame of a cycle on opposite sides of a wheel upon which the brake operates. A brake pad assembly is attached to each of the brake arms for positioning a brake pad in a select position with respect to a tire rim. Distal ends of the brake arms are attached by a straddle cable and a brake cable operated by a lever on the handle bar of the cycle is attached to the center of the straddle cable. Squeezing the brake lever on the handle bar draws the brake cable upward which in turn pulls up on the straddle cable, thereby pulling the brake arms toward one another and bringing the brake pads into contact with the wheel rim. In the typical brake assembly, springs are provided between the brake arms and the bicycle frame for biasing the brake arms away from one another and away from the rim. Conventional cantilever brakes for bicycles are disclosed in Yoshagi, U.S. Pat. No. 5,058,450, and Nagano, U.S. Pat. No. 5,373,918. The attachment studs are the uniform structures as can be observed in both the U.S. Pat. No. '450 and the U.S. Pat. No. '918 patent. Attachment studs include a uniform diameter body having an increased diameter shoulder at a proximal end of the attachment stud.
As illustrated in the U.S. Pat. No. '450 patent and the U.S. Pat. No. '918 patent, standard cantilever brake arms have a non-symmetric shape and a dedicated point of attachment of a brake pad assembly to the brake arm. As a result, it is difficult or impossible to move the brake pad assembly up and down enough to make the cantilever brakes fully adaptable to all cycles. In addition, these designs provide very limited ability to rotate the brake pad assembly about a lengthwise axis of the brake arm, making it difficult to effectively adjust the "toe" of the brake pad. Furthermore, the non-symmetric shape of the brake arm results in a brake arm which is of a lesser dimension (and therefore weaker) normal to the direction of brake arm actuation, leaving the brake arm subject to deformation or damage from impact normal to their direction of movement.
One solution to some of these serious problems with conventional brake arm structures is a cylindrical brake arm. Marinovative, of Marin County, Calif., was an early maker of brakes featuring cylindrical brake arms. Other brake manufacturers have also incorporated the cylindrical brake arm design. These brakes solved some of the problems discussed above. Most notably, some designs provided a full range of movement of the brake pads lengthwise of the brake arm, as well as rotation about a lengthwise axis of the brake arms. However, these brakes created some new problems. In particular, standard brake designs, including the previously discussed cylindrical brake arm designs, mount the brake arm to a brake arm base so that the brake arm extends from above the uniform diameter portion of an attachment stud. This design is illustrated in FIG. 4. A problem with this design is that commonly the point of attachment of the brake pad assembly to the brake arm extends beyond the end of the attachment stud (see FIG. 4). The prior art recognized the advantages of positioning the point of attachment of the brake pad assembly over the attachment stud. In order to accomplish this, prior art structures provided non-linear or bent brake arms. Examples are the U.S. Pat. No. '918 patent discussed above and Yoshagi, U.S. Pat. No. 5,133,432. This solution is not available for cylindrical brake arms because it is difficult to bend a cylinder in this manner and such bending restricts the lengthwise movement of a brake pad adjustment assembly, thereby negating in part the adjustability advantage of cylindrical brake arms. As a result, prior art cylindrical brake arm cantilever brakes have the brake pad adjustment assembly cantilevered beyond the end of the stud. As the brakes are used the studs are deflected, resulting in the brake pad connecting with the tire rim unevenly, as illustrated in FIG. 4. This causes decreased braking efficiency and uneven brake pad wear. Deflection of the stud in this manner also creates a "soft" feel in the brakes, making the brakes seem less responsive. In addition, the cantilever effect leads to uneven wear between the brake arm base and the attachment stud. The present invention is directed toward overcoming one or more of the deficiencies discussed above.